Giz Explains: What It Takes to Restore Cellular Service After a Hurricane

Hurricane Sandy and left an estimated eight million people without power. Plenty more have spotty cellular service—if they have any at all. But why do some people get a signal when others don’t? And what does it take to get a wireless service back online?

As of yesterday, FCC Chairman Julius Genachowski estimated that 25 percent of all cell sites—regardless of server—were inoperable throughout 158 counties in 10 states spanning Virginia to Massachusetts. That’s actually a fantastically small amount compared to the 2005 Hurricane Katrina disaster that effectively wiped out 70 percent of the telecommunications infrastructure. It had “completely collapsed,” said Curtis Papke, an engineer at Idaho National Laboratory told Quartz. “Even if you had cell coverage, there was no one at the 911 centres to answer the call.” And nothing calms a terrified public after devastating natural disasters quite like getting 911’s answering machine.

To prevent this sort of thing happening again in future storms, *ahem*, the FCC issued the Katrina Panel Order, a set of binding guideline dictating that wireless carriers “ensure network reliability and reliance” by “[provisioning] their cell sites and switches with batteries to power them when electrical grids fail” and “maintain permanent generators at all of the switches and critical cell sites, as well as an inventory of backup power generators to recharge the batteries during extended commercial power failures.” Basically, the FCC told the nation’s wireless carriers that they needed install backup power sources on all of their cell towers to keep them running if the public grid fails. The wireless carriers responded as one would expect—they stalled and sued to block the ruling, claiming that they had already performed similar upgrades on 90-percent of their equipment.

While the FCC’s order has been effectively shelved, the carriers apparently have been busy storm-proofing their cellular equipment. “The Verizon Wireless network withstood the severe weather along the Eastern Seaboard resulting from Hurricane Sandy and is functioning solidly — particularly in the hardest-hit areas in the Northeast, where more than 94 percent of our cell sites are up and running,” Nicola Palmer, vice president-network and chief technical officer for Verizon Wireless, boasted in a press release Tuesday.

Power outages aren’t the only cause of cell tower failure, mind you. Towers can sustain physical damage from winds and debris or their cabling back to the network switching subsystems can be severed. And since cellular networks are designed to share loads among nodes (the individual towers), knocking out a few nodes in each cell (read: service area) puts added strain on those remaining, leading to dropped calls or the inability to connect at all.

Unfortunately, repairing physically damaged towers means getting service technicians into disaster areas that must first be deemed safe by local authorities. And even if they do have access, as Bob Mudge, president of Verizon’s Consumer and Mass Business division explained, “Some restorals will require physical rebuilding of our facilities, and others will require the return of commercial power.”